Some mobile electronic devices blink their light emitting diodes (LEDs) to indicate an incoming call when the incoming call arrives. The Central Processing Unit (CPU) of the mobile electronic devices must be activated to allow an LED to blink. Activation of the CPU may cause high power consumption in a mobile electronic device since the CPU may be kept active for a long period of time to keep the LED on for the long period of time. Hence there is a need for mobile electronic devices in which power consumption is low even if their LEDs are turned on for long periods of time.